The surgical procedure for heart valve replacement typically involves removing a diseased heart valve and implanting an artificial heart valve device. Removal of the diseased heart valve generally involves cutting the valve from the heart to form an annulus in which the replacement valve is implanted. Conventional cutting processes for forming the heart valve annulus involve the use of scissor devices to cut the existing valve tissue from the heart. Frequently, the valve is extremely calcified and irregular in shape and thickness, thus to remove the valve in its entirety, exertion of considerable mechanical forces are required, which can cause cutting the valve in small pieces and releasing chunks of calcium or tissue.
This conventional use of scissors often produces imprecise cuts and leaves an irregular annulus in which the surgeon must then attach or suture the replacement valve. Because of the irregular annulus left by the use of scissors and other debriding instruments, the suturing process can be quite time-consuming. In particular, the surgeon must ensure that there are no openings around the replacement valve that would allow blood to flow from the heart chamber without passing through the replacement valve. More importantly, a considerable force cannot be used to remove a calcified valve when a device is placed and is manipulated percutaneously, as in through a transvascular catheter placed through a peripheral artery, such as the femoral artery.
Another apparatus that could be used to remove a diseased heart valve is an apparatus having an annulus cutter that is moved toward a backup plate in order to engage the tissue to be removed. The rotation of the annulus cutter by a surgeon would cut the tissue. The tissue is then captured by the cutting device and the backup plate. Such a device is described in International Publication No. WO 99/59482, which is incorporated in its entirety by reference herein. However, this procedure has several disadvantages. For example, the cut may still be imprecise and furthermore, parts of the cut tissue can inadvertently be dislodged from the capturing device. The dislodged tissue can cause an occlusion and embolism. More importantly, a large diameter cutting annulus could not be placed percutaneously through a small diameter peripheral artery, such as the femoral artery. In addition, it would be difficult and risky to transmit the considerable mechanical forces needed to cut a calcified valve through a percutaneously placed mechanical cutting device.
Accordingly, a need exists for a new improved method and apparatus for cutting living tissue, such as a heart valve.